package com.ks.common.util;

import lombok.extern.slf4j.Slf4j;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.util.*;

/**
 * 常见工具类
 *
 * @author KingAusten
 * @date 2022/08/17 18:02:29
 */
@Slf4j
public class CommonUtil{

    /**
     * 获取随机长度的串
     *
     * @param length
     * @return
     */
    private static final String ALL_CHAR_NUM = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

    /**
     * 获取ip
     *
     * @param request
     *
     * @return
     */
    public static String getIpAddr(HttpServletRequest request){

        String ipAddress = null;
        try{
            ipAddress = request.getHeader("x-forwarded-for");
            System.out.println("x-forwarded-for=" + ipAddress);
            if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)){
                ipAddress = request.getHeader("Proxy-Client-IP");
                System.out.println("Proxy-Client-IP=" + ipAddress);
            }
            if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)){
                ipAddress = request.getHeader("WL-Proxy-Client-IP");
                System.out.println("WL-Proxy-Client-IP=" + ipAddress);
            }
            if(ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)){
                ipAddress = request.getRemoteAddr();
                System.out.println("getRemoteAddr=" + ipAddress);
                if(ipAddress.equals("127.0.0.1")){
                    // 根据网卡取本机配置的IP
                    InetAddress inet = null;
                    try{
                        inet = InetAddress.getLocalHost();
                    }
                    catch(UnknownHostException e){
                        e.printStackTrace();
                    }
                    ipAddress = inet.getHostAddress();
                    System.out.println("getHostAddress=" + ipAddress);
                }
            }
            // 对于通过多个代理的情况，第一个IP为客户端真实IP,多个IP按照','分割
            if(ipAddress != null && ipAddress.length() > 15){
                // "***.***.***.***".length()
                // = 15
                if(ipAddress.indexOf(",") > 0){
                    ipAddress = ipAddress.substring(0,ipAddress.indexOf(","));
                }
            }
        }
        catch(Exception e){
            ipAddress = "";
        }
        return ipAddress;
    }

    /**
     * 获取全部请求头
     *
     * @param request
     *
     * @return
     */
    public static Map<String,String> getAllRequestHeader(HttpServletRequest request){

        Enumeration<String> headerNames = request.getHeaderNames();
        Map<String,String> map = new HashMap<>();
        while(headerNames.hasMoreElements()){
            String key = headerNames.nextElement();
            //根据名称获取请求头的值
            String value = request.getHeader(key);
            map.put(key,value);
        }

        return map;
    }

    /**
     * MD5加密
     *
     * @param data
     *
     * @return
     */
    public static String MD5(String data){

        try{
            MessageDigest md = MessageDigest.getInstance("MD5");
            byte[] array = md.digest(data.getBytes(StandardCharsets.UTF_8));
            StringBuilder sb = new StringBuilder();
            for(byte item: array){
                sb.append(Integer.toHexString((item & 0xFF) | 0x100),1,3);
            }

            return sb.toString()
                    .toUpperCase();
        }
        catch(Exception exception){
        }
        return null;

    }

    /**
     * 获取验证码随机数
     *
     * @param length
     *
     * @return
     */
    public static String getRandomCode(int length){

        String sources = "0123456789";
        Random random = new Random();
        StringBuilder sb = new StringBuilder();
        for(int j = 0;j < length;j++){
            sb.append(sources.charAt(random.nextInt(9)));
        }
        return sb.toString();
    }

    /**
     * 获取当前时间戳
     *
     * @return
     */
    public static long getCurrentTimestamp(){

        return System.currentTimeMillis();
    }

    /**
     * 生成uuid
     *
     * @return
     */
    public static String generateUUID(){

        return UUID.randomUUID()
                .toString()
                .replaceAll("-","")
                .substring(0,32);
    }

    public static String getStringNumRandom(int length){
        //生成随机数字和字母,
        Random random = new Random();
        StringBuilder saltString = new StringBuilder(length);
        for(int i = 1;i <= length;++ i){
            saltString.append(ALL_CHAR_NUM.charAt(random.nextInt(ALL_CHAR_NUM.length())));
        }
        return saltString.toString();
    }


    /**
     * 响应json数据给前端
     *
     * @param response
     * @param obj
     */
    public static void sendJsonMessage(HttpServletResponse response,Object obj){

        response.setContentType("application/json; charset=utf-8");

        try(PrintWriter writer = response.getWriter()){
            writer.print(JsonUtil.obj2Json(obj));
            response.flushBuffer();

        }
        catch(IOException e){
            log.warn("响应json数据给前端异常:{ }",e);
        }


    }

    /**
     * 响应HTML数据给前端
     *
     * @param response
     * @param jsonData
     */
    public static void sendHtmlMessage(HttpServletResponse response,JsonData jsonData){

        response.setContentType("text/html; charset=utf-8");

        try(PrintWriter writer = response.getWriter()){
            writer.write(jsonData.getData()
                                 .toString());
            writer.flush();
        }
        catch(IOException e){
            log.warn("响应json数据给前端异常:{ }",e);
        }

    }

}
